As the best-selling compact family car after the Ford Focus, Vauxhall knows not to mess with a successful formula – hence the Astra’s mildly updated looks. The new 1.6 Turbo engine is brilliant, though; it’s powerful, efficient and very clean. And while the Focus still has the edge, it makes for a fun driving experience. With prices increasing only slightly given the considerable leap in performance, the Astra represents better value than ever.

Don’t worry; your eyes aren’t deceiving you. This really is the revised and updated Astra. But while the minor cosmetic changes aren’t likely to get many pulses racing among enthusiasts, what’s now sitting under the bonnet most definitely will.

That’s because flagship versions of the compact family hatchback get the manufacturer’s latest 1.6-litre turbocharged engine – a unit that already takes a starring role in the Corsa VXR and is set to appear in the forthcoming all-new Vectra in 2008.

Replacing the old Astra’s 170bhp and 200bhp 2.0-litre turbo powerplants, the new engine pumps out a healthy 177bhp and a useful 230Nm of torque. It’s mated to a six-speed manual gearbox as standard.

Completing the benchmark sprint from 0-60mph in 7.8 seconds, and accelerating on to a maximum speed of 137mph, the newcomer is quicker than the outgoing 170bhp car (which covered 0-60mph in 8.1 seconds). It’s nearly as fast as the 200bhp variant (7.7 seconds), and has enough pace at its disposal to keep up with today’s hottest hatches.

But the figures alone can’t do the new engine justice, as one of its most impressive features is its power delivery. The strong low-down urge continues throughout the rev range, making for rapid progress and easy overtaking. It’s also commendably smooth, and quiet at motorway speeds.

You would expect there to be a price to pay for this performance – both at the fuel pumps and in terms of emissions. But the new 1.6-litre manages to be more economical and cleaner than the previous 170bhp 2.0, returning 36.7mpg on the combined cycle (up 6mpg) and cutting CO2 output from 216g/km to 185g/km.

That would save company drivers as much as £758 a year in benefit-in-kind tax, and private buyers would also see their road fund licence fee drop from £190 to £150. Yet while the new engine is powerful, frugal and clean, most customers – whether business or retail – would be better off with the 150bhp 1.9-litre CDTI turbodiesel Astra instead.

As well as the turbo, the revised Astra is offered with an updated 1.6-litre Twinport petrol powerplant. This benefits from a power hike, taking it from 105bhp to 115bhp.

Visual changes have been kept to a minimum, though. There are new lights all-round and a restyled front bumper, while inside you get a choice of piano black or matt chrome trim.

The driving experience is as good as ever, with a firm but well controlled ride, excellent agility and accurate steering – although it’s not as sharp as the set-up in Ford’s Focus.

Prices haven’t changed drastically, either. The new 1.6-litre Turbo is only £220 more than the old 2.0, while other models rise see an increase of a mere £15. It all adds up to an even better package than before.